Auto-generated JS API docs & TS cleanup

[letmaik]

Fixes #1765.

This uses sphinx-js and typedoc to generate API docs for the built-in parts of CCF. It does not (yet?) document the utility TypeScript module that can optionally be used for dealing with type conversions of KV map keys/values.

sphinx-js' TypeScript support is basic and the project acknowledges that and doesn't intend to work on it (since Mozilla doesn't use TypeScript themselves). Any improvements typically come from community PRs. I tried to work around various issues but it's not as pretty as it could be.

I also took the opportunity to split the built-in from the utility parts and move them into separate modules. There are no "automatic" breaking changes for existing apps since the original ccf.ts module has to be vendored.

[letmaik]

sphinx-js doesn't support newer versions yet.

[letmaik]

Probably util is not the best name. Since these are all KV helpers, maybe something with kv in the name?

[achamayou]

app.ts to match the C++ ccfapp namespace?

[letmaik]

I don't think that's a good name. We may have more modules in the future and collectively they may be in the "ccfapp" namespace but modules != namespace.

[letmaik]

Let's ignore this for now and think about it again when we make it into a library.

[ghost]

letmaik/js-api-docs@20568 aka 20210315.22 vs main ewma over 20 builds from 20172 to 20556

[achamayou]

Two things that are unrelated to documentation but which this PR made obvious to me:

1. We seem to have taken a rather random view to capitalising acronyms, so we have RsaOaep-like things and AESKW-like things. I don't particularly care which one we go with (although the latter makes more sense to me), but it's important to be consistent.
2. All the crypto calls like generate key, wrap etc should be under ccf.crypto, and we should perhaps have ccf.conv for the conversion calls.

[achamayou]

Thanks you for setting this up, I expect it will make the JS/TS interface considerably easier to use in practice.

[letmaik]

Two things that are unrelated to documentation but which this PR made obvious to me:

1. We seem to have taken a rather random view to capitalising acronyms, so we have RsaOaep-like things and AESKW-like things. I don't particularly care which one we go with (although the latter makes more sense to me), but it's important to be consistent.

2. All the crypto calls like generate key, wrap etc should be under `ccf.crypto`, and we should perhaps have `ccf.conv` for the conversion calls.

Yep, I opened #2315 for that.